2. Let the characters engage with the historical details. This goes along with that “show don’t tell” truism writers are told all the time. Rather than just dumping a bunch of facts on the poor reader, let your characters interact with these details with all these senses. Let them smell the offal dumped onto the cobblestone streets. Let them squint in the fading light of the tallow candles. Let them feel the tingling sensation as the physician places a leech on their bare skin.